If you have a gram scale measure doses and mix into a 5g bucket then test results to establish adjustment values. (what I did)

W/O a scale do leveled mixing spoons 1/2 & 1tsp but realize that compaction and moisture effect the values slightly more than the scale but it's still minor.

Gold Finger

11-17-2012 11:57 PM

Also, I believe potassium carbonate (K2CO3) adds ~33mg/l K+ along with each 1 degree of hardness added by the CO3 just like K2SO4 does. It works well but you have to understand and want the K+ ratio. lots of extra K seems fine, but plants don't need KH so it's just a pH buffer issue. If you have two or three degrees in your tap I would not bother raising it. Over four degrees can limit some plants. Otherwise K2SO3 is supposed to be a good way to raise KH.